1. Field of the Invention
The present invention relates to an image forming apparatus and a thumbnail image generating method.
2. Description of Related Art
In recent years, an image forming apparatus has become widely used, in which image data read from a document, image data obtained form an external terminal, and the like can be saved in the medium-to-long term. The saved image data is subjected to image forming at a desirable timing by an instruction operation of a user.
When a piece of image data is selected among the saved image data by a user, file names or thumbnail images of the available choices of image data are displayed in a display section which is attached to the image forming apparatus. The thumbnail image is an image used for reference which is generated by reducing the saved image data, or the like.
In a case where a large amount of image data is being saved, it is difficult for a user to judge the content of the image data when only the file names of pieces of image data are displayed. Accordingly, the judgment becomes easier by displaying the thumbnail images.
Generally, the generating processing of the thumbnail image is performed at a separate timing from the image processing of original image data of the thumbnail image. For example, first, the original image data is saved in a predetermined memory. Subsequently, the Central Processing Unit (CPU) accesses the memory to copy the original image data, and performs reducing processing, and the like, for the copied image data. Thus, the thumbnail image is generated. Further, while the thumbnail images are generated, the original image data is subjected to various processing such as image processing, and the like.
In the generating processing of the thumbnail images performed in the above described manner, the larger the data amount of the thumbnail images is, the longer the time for generating processing thereof is to be spent. Further, there may be a case where the image processing and the like of the original image data take time, due to the generating processing of the thumbnail images.
Considering the fact that the thumbnail images are used for assisting the original image data, it is preferable to reduce the time spent for the generating processing of the thumbnail images as much as possible. Further, when the generating processing of the thumbnail images is performed, it is necessary that processing of the original image data should not be influenced by the generating processing of the thumbnail images.
In order to solve the problems caused by generating the thumbnail images, the following techniques described in Japanese Patent Application Laid-Open Publication No. 2002-77803, Japanese Patent Application Laid-Open Publication No. 2005-341382, and Japanese Patent Application Laid-Open Publication No. 2006-115000 are disclosed.
According to Japanese Patent Application Laid-Open Publication No. 2002-77803, disclosed is a video information recording apparatus to create thumbnail images when video data which is once recorded in a memory is encoded (performed with compression processing and the like). Thereby, the time for creating the thumbnail images needed when reproducing/editing the video data is no longer necessary.
Further, according to Japanese Patent Application Laid-Open Publication No. 2005-341382, disclosed is an image processing apparatus to perform generating processing of thumbnail images in parallel with compression and recording processing of input image data. Thereby, the generating processing of the thumbnail images need not be separately performed after the photographing of the images. Thus, the time spent separately for the generating processing of the thumbnail images is no longer necessary, in the same manner as the disclosure of Japanese Patent Application Laid-Open Publication No. 2002-77803.
Moreover, according to Japanese Patent Application Laid-Open Publication No. 2006-115000, disclosed is an image processing apparatus comprising a plurality of memories, in which the generating processing of the thumbnail images is performed in a predetermined memory, whichever memory the original compression image data of the thumbnail image may be saved in. Thereby, the generating processing of the thumbnail images and the processing of a job with higher priority are not performed at the same time in the same memory. Thus, hindering the processing of the job with higher priority by the generating processing of the thumbnail images can be prevented.
However, according to the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2002-77803, the video data is once recorded in the memory. Accordingly, the memory in which the video data is recorded needs to be accessed when generating the thumbnail images, thus the processing time for accessing is required.
Further, according to the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2005-341382, the thumbnail images are generated in parallel with the processing in which the image data is recorded in the memory, thus the problem caused in Japanese Patent Application Laid-Open Publication No. 2002-77803 may be solved.
However, the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2005-341382 is applied for generating thumbnail images especially for moving images, and fails to disclose the applicability for a still image for printing. For example, in order to generate a thumbnail image for a still image for printing comprising a plurality of colors, it is necessary that the thumbnail image is generated in consideration of the image data of each of the colors of C (cyan), M (magenta), Y (yellow), and K (black), and that the generated thumbnail image is displayed in the display section.
Moreover, according to Japanese Patent Application Laid-Open Publication No. 2006-115000, although the generating processing of the thumbnail image for a still image is disclosed, reducing the time spent for the generating processing of the thumbnail image is not disclosed.